1. Technical Field
The present invention relates to an information acquisition apparatus and an information acquisition method.
2. Related Art
Apparatuses that acquire biological information of a subject in a noninvasive fashion are in use. Such apparatuses put a small burden on subjects, and have high safety. One such apparatus is disclosed in JP-A-11-323 as a noninvasive blood analyzing apparatus that acquires information of blood components using light. According to this publication, a sensor is brought into contact with the subject's skin surface, and measurement light is applied into the body of the subject. Hemoglobin in the blood absorbs light of specific wavelengths. The reflected light from the subject is analyzed to detect the proportion of the oxygenated form of hemoglobin. The apparatus also detects biological information such as information of blood components.
The apparatus described in the foregoing publication detects blood information from a blood vessel selected as a test object. The apparatus emits light from a light source unit, and an imaging section receives light. The light source unit and the imaging section are electronic components, and undergo changes over time. The quantity of light from the light source decreases, and the imaging section lowers its sensitivity to light. The accuracy of the detected light information thus decreases with time. There accordingly is a need for an information acquisition apparatus that can accurately detect the characteristics of reflected light from an object even when sensor sensitivity changes with time.